The present invention relates to flexible sheet material dispensers, such as dispensers for paper towels. The invention particularly relates to a method for cutting and dispensing individual sheets of creped paper toweling and to apparatus for practicing such method.
Dispensers for continuous, unperforated flexible sheet material, such as paper toweling, are well known. Such dispensers include those in which the sheets are simply torn from the web by the user or, more commonly, those in which the sheets are completely severed by a cutter in the dispenser for removal by a user. Also included are dispensers in which the cutter in the dispenser produces a line of cut containing residual segments of uncut material in the web defining the desired sheet that is, thereafter, completely severed by the user upon removal. The first-mentioned type of dispenser has the disadvantage that it employs no control against the length of web material dispensed prior to severance such that a user can wastefully pull out an excessive length of material prior to tearing it off. Such dispensers have the further disadvantage that, following removal of the sheet by the user, the next user must pay out a succeeding length of web by pulling a handle, turning a crank, or activating some other device that requires touching or handling the mechanism which, in the environment that such dispensers are located, i.e., wash rooms and the like, is undesirable.
Accordingly, in dispensers of more recent design these disadvantages have been overcome by the utilization of cutting devices in the dispenser that cut the web material to sheet length as the user pulls it from the dispenser. Such apparatus typically involve a feed roll from which paper is supplied by a user grasping the free end of the web that is disposed outside the dispenser chassis and pulling it to operate the feed roll. In these devices a stored energy mechanism, such as a spring, may be associated with the feed roll to acrid/ate the cutter and/or to conduct the web material from the dispenser. As mentioned, cutters for such dispensers may cut the material to totally sever a sheet from the web or, alternatively, may produce such a cut as will only partially sever the web, leaving the sheet connected to the web by means of one or more unsevered segments of residual web material, for removal by the user following conduct of the sheet from the dispenser by the feed roll.
Dispensers of the concerned type in which a cutter operates in conjunction with a feed roll and in which the motive force for the operation of the dispenser is provided by the web material being pulled by the user are exemplified by U.S. Pat. Nos. 3,575,328, 4,122,738 and 4,621,755. These dispensers each characteristically employ an over-center spring drive that is loaded during a first portion of the operating cycle of the mechanism during which cutting is normally effected as the web material, in friction contact with the feed roll, is pulled from the dispenser. After completion of the cutting operation, when the feed roll is rotated beyond the over-center condition, the spring is unloaded and the energy stored therein is utilized to drive the feed roll to conduct the cut web portion from the dispenser and to dispose the leading end of the succeeding length of web material at a location outside the dispenser chassis where it can be readily grasped by the next user.
In each of U.S. Pat. Nos. 3,575,328, 4,122,738 and 4,621,755, which typify the concerned devices, the length of web material removed from the dispenser is controlled by means of a positive or hard stop mechanism that limits the amount of rotation permitted the feed roll to one revolution and, concomitantly, the length of web material removed corresponding substantially to the developed circumference of the exterior surface of the feed roll. In the mechanism described in U.S. Pat. No. 3,575,328 in which the cutting knife produces a perforated, or only partially severed, line of cut, the stop mechanism serves the additional function of providing an abrupt arresting force on the web material whereupon the sheet defined by the perforated line of cut is caused to be completely severed by the pulling force imparted by the user.
It has been determined that positive stop mechanisms manifest significant undesirable characteristics. The more obvious of these undesirable characteristics are the additional cost that they add to a dispenser, both in terms of purchase price and in terms of the additional space required to accommodate them. Also, since these mechanisms are subject to repeated impact stresses, they are prone to frequent malfunction and breakage.
Furthermore, such positive stop mechanisms are particularly disadvantageous when employed with apparatus intended to dispense partially severed soft, relatively weak flexible sheet material. Under these conditions, the web material may become separated by tearing along the line of cut before the stop mechanism is activated, whereupon the next user can only remove an unusable limited amount of material before the stop is activated thereby preventing the removal of any more material.
Obviously, such problems can be overcome by increasing the strength of the unsevered segments of web material that hold the web together along the line of cut; however, when this is done, particularly when the material is highly absorbent and the user's hands are wet, the material cannot be relied upon to sever along the line of cut when the stop mechanism is activated. Instead, the pulling action of the user frequently results in severance of only the wet part of the web material held in the user's hands, which, more often than not, becomes untidy debris deposited on the floor beneath the dispenser.
It is to the amelioration of the above described problems, therefore, to which the present invention is directed.